This invention relates generally to the treatment of drainwater which passes into the piping of a drainage system by way of a storm drain and relates, more particularly, to catch basins or other gravitational separators into which drainwater is routed and filtration systems through which drainwater is routed for the purposes of filtering contaminants from the drainwater.
It is known that residue from oil and gasoline spills at service stations, parking lots or similar sites commonly remains at the site of the spill until it is washed away with water by way of a rainfall or a hose-cleaning operation. of, course, as the residue and/or spilled material is washed to a drain, it is likely to be carried to and mixed with the water supply (e.g. lakes, etc.) from which drinkable water is taken. Similar problems and environmental concerns arise at alternative sites, such as in a leaching pool designed as a detention basin, for filtering, for example, wastewater, stormwater, free-phased organics, petroleum spills, nonpoint source discharge water, vehicle washdown wastewater, wastewater from secondary containment dikes, excavation and construction sites, underground storage tank removals, emergency response conditions, remote wash down areas, and captured water at stream crossings for timber cutting sites. It would be desirable to provide means for separating unwanted contaminants from drainwater which is washed into a drainage system.
It is an object of the present invention to provide a new and improved gravitational separator into which drainwater is routed when conducted along a drainage system.
Another object of the present invention is to provide such a separator which is easily serviceable and is particularly well-suited for use with a filtration system through which drainwater which enters a storm drain is directed for the purpose of filtering the drainwater.
Still another object of the present invention is to provide a new and improved drainwater treatment system which is positionable within a horizontal flow passage of a storm drain system and which provides an improvement upon the structure and filtration capabilities of the drainwater treatment systems of the prior art.
Yet another object of the present invention is to provide such a treatment system which provides a relatively high exposure of drainwater to filter medium as drainwater flows through the treatment system.
A further object of the present invention is to provide such a system which is uncomplicated in construction and effective in operation.
This invention resides in a gravitational separator positionable within a drainage system having an upstream pipe portion having an outlet through which drainwater enters the separator and a downstream pipe portion having an inlet through which drainwater exits the separator.
The treatment system includes means for defining a flow cavity having a bottom and a substantially circular sidewalls extending upwardly from the bottom. The sidewalls include an entrance opening which is connectable in flow communication with the outlet of the upstream pipe portion and an exit opening which is connectable in flow communication with the inlet end of the downstream pipe portion. Furthermore, the entrance and exit openings are disposed in an elevated and spaced condition above the bottom of the cavity-defining means.
In addition, the cavity-defining means is positionable in such a relation to the upstream pipe portion so that drainwater which enters the cavity-defining means through the entrance opening thereof is directed substantially tangentially along the inside surface of the sidewalls to impart a swirling motion to drainwater collected within the cavity-defining means. The separator further includes baffle means supported within the cavity-defining means and adjacent the exit opening of the cavity-defining means for isolating the exit opening from swirling motion of drainwater collected within the cavity-defining means yet permit drainwater to exit the cavity-defining means through the exit opening when the level of drainwater collected within the cavity-defining means reaches the level of the exit opening.
In one aspect of the present invention, the separator is used in conjunction with a drainwater filtration system disposed downstream of the exit opening of the cavity-defining means so that drainwater which exits the cavity-defining means is subsequently routed through the filtration system.